Changes in v2:
* Basically moved arm64_print_stackframe_entry() after arm64_unwind_frame()
  in arm64_back_trace_cmd() to make the output consistent with the format
  on x86
  Then, we had to calculate the end address of a stack frame, frame_top,
  for particular cases.

-Takahiro AKASHI

======8<======
>From d8683645599a238578a0f586af563bc9f847d52c Mon Sep 17 00:00:00 2001
From: AKASHI Takahiro <[email protected]>
Date: Wed, 8 Jun 2016 11:14:22 +0900
Subject: [PATCH v2] arm64: dump a stack frame based on fp

Signed-off-by: AKASHI Takahiro <[email protected]>
---
 arm64.c | 140 ++++++++++++++++++++++++++++++++++++++++++++++++----------------
 defs.h  |   5 +++
 2 files changed, 110 insertions(+), 35 deletions(-)

diff --git a/arm64.c b/arm64.c
index bdea79c..7b5b394 100644
--- a/arm64.c
+++ b/arm64.c
@@ -43,9 +43,10 @@ static void arm64_stackframe_init(void);
 static int arm64_eframe_search(struct bt_info *);
 static int arm64_is_kernel_exception_frame(struct bt_info *, ulong);
 static int arm64_in_exception_text(ulong);
+static int arm64_in_exp_entry(ulong);
 static void arm64_back_trace_cmd(struct bt_info *);
 static void arm64_print_text_symbols(struct bt_info *, struct arm64_stackframe 
*, FILE *);
-static int arm64_print_stackframe_entry(struct bt_info *, int, struct 
arm64_stackframe *, FILE *);
+static int arm64_print_stackframe_entry(struct bt_info *, int, struct 
arm64_stackframe *, struct arm64_stackframe *, FILE *);
 static void arm64_display_full_frame(struct bt_info *, ulong);
 static int arm64_unwind_frame(struct bt_info *, struct arm64_stackframe *);
 static int arm64_get_dumpfile_stackframe(struct bt_info *, struct 
arm64_stackframe *);
@@ -597,6 +598,10 @@ arm64_dump_machdep_table(ulong arg)
        fprintf(fp, "  __exception_text_end: %lx\n", ms->__exception_text_end);
        fprintf(fp, " __irqentry_text_start: %lx\n", ms->__irqentry_text_start);
        fprintf(fp, "   __irqentry_text_end: %lx\n", ms->__irqentry_text_end);
+       fprintf(fp, "      exp_entry1_start: %lx\n", ms->exp_entry1_start);
+       fprintf(fp, "        exp_entry1_end: %lx\n", ms->exp_entry1_end);
+       fprintf(fp, "      exp_entry2_start: %lx\n", ms->exp_entry2_start);
+       fprintf(fp, "        exp_entry2_end: %lx\n", ms->exp_entry2_end);
        fprintf(fp, "       panic_task_regs: %lx\n", 
(ulong)ms->panic_task_regs);
        fprintf(fp, "         PTE_PROT_NONE: %lx\n", ms->PTE_PROT_NONE);
        fprintf(fp, "              PTE_FILE: ");
@@ -1283,6 +1288,16 @@ arm64_stackframe_init(void)
                machdep->machspec->__irqentry_text_end = sp2->value; 
        } 
 
+       if ((sp1 = kernel_symbol_search("vectors")) &&
+           (sp1n = kernel_symbol_search("cpu_switch_to")) &&
+           (sp2 = kernel_symbol_search("ret_fast_syscall")) &&
+           (sp2n = kernel_symbol_search("sys_rt_sigreturn_wrapper"))) {
+               machdep->machspec->exp_entry1_start = sp1->value;
+               machdep->machspec->exp_entry1_end = sp1n->value;
+               machdep->machspec->exp_entry2_start = sp2->value;
+               machdep->machspec->exp_entry2_end = sp2n->value;
+       }
+
        if ((sp1 = kernel_symbol_search("crash_kexec")) &&
            (sp1n = next_symbol(NULL, sp1)) && 
            (sp2 = kernel_symbol_search("crash_save_cpu")) &&
@@ -1484,18 +1499,54 @@ arm64_in_exception_text(ulong ptr)
        return FALSE;
 }
 
+static int
+arm64_in_exp_entry(ulong addr)
+{
+       struct machine_specific *ms;
+
+       ms = machdep->machspec;
+       if ((ms->exp_entry1_start <= addr) && (addr < ms->exp_entry1_end))
+               return TRUE;
+       if ((ms->exp_entry2_start <= addr) && (addr < ms->exp_entry2_end))
+               return TRUE;
+       return FALSE;
+}
+
 #define BACKTRACE_CONTINUE        (1)
 #define BACKTRACE_COMPLETE_KERNEL (2)
-#define BACKTRACE_COMPLETE_USER   (3)
 
 static int 
-arm64_print_stackframe_entry(struct bt_info *bt, int level, struct 
arm64_stackframe *frame, FILE *ofp)
+arm64_print_stackframe_entry(struct bt_info *bt, int level, struct 
arm64_stackframe *frame, struct arm64_stackframe *caller_frame, FILE *ofp)
 {
        char *name, *name_plus_offset;
        ulong symbol_offset;
        struct syment *sp;
        struct load_module *lm;
        char buf[BUFSIZE];
+       unsigned long frame_top;
+
+       if (caller_frame->fp) {
+#if 0 /* FIXME: Need to debug here */
+               if (arm64_in_exp_entry(caller_frame->pc))
+                       frame_top = caller_frame->fp - sizeof(struct 
arm64_pt_regs);
+               else
+#endif
+                       frame_top = caller_frame->fp;
+       } else if (frame->fp && !arm64_in_exp_entry(frame->pc))
+               frame_top = bt->stacktop - USER_EFRAME_OFFSET;
+       else
+               frame_top = bt->stacktop - 0x10;
+
+       if (CRASHDEBUG(1)) {
+               fprintf(ofp, "    cur sp:%016lx fp:%016lx pc:%016lx\n",
+                       frame->sp, frame->fp, frame->pc);
+               fprintf(ofp, "    nxt sp:%016lx fp:%016lx pc:%016lx\n",
+                       caller_frame->sp, caller_frame->fp, caller_frame->pc);
+
+               fprintf(ofp, "    frame: <%lx-%lx> check(%d, %d)\n",
+                       bt->frameptr, frame_top,
+                       INSTACK(frame_top, bt), INSTACK(bt->frameptr, bt));
+       }
 
         name = closest_symbol(frame->pc);
         name_plus_offset = NULL;
@@ -1507,13 +1558,16 @@ arm64_print_stackframe_entry(struct bt_info *bt, int 
level, struct arm64_stackfr
                                 value_to_symstr(frame->pc, buf, bt->radix);
         }
 
-       if (bt->flags & BT_FULL) {
-               arm64_display_full_frame(bt, frame->sp);
-               bt->frameptr = frame->sp;
-       }
+       if (bt->flags & BT_FULL)
+               arm64_display_full_frame(bt, frame_top);
+       bt->frameptr = frame_top;
 
         fprintf(ofp, "%s#%d [%8lx] %s at %lx", level < 10 ? " " : "", level,
-                frame->sp, name_plus_offset ? name_plus_offset : name, 
frame->pc);
+#if 1 /* FIXME */
+                (frame->fp ? : frame->sp), name_plus_offset ? name_plus_offset 
: name, frame->pc);
+#else
+                frame->fp, name_plus_offset ? name_plus_offset : name, 
frame->pc);
+#endif
 
        if (BT_REFERENCE_CHECK(bt))
                arm64_do_bt_reference_check(bt, frame->pc, name);
@@ -1571,12 +1625,10 @@ arm64_unwind_frame(struct bt_info *bt, struct 
arm64_stackframe *frame)
 {
        unsigned long high, low, fp;
        unsigned long stack_mask;
-       unsigned long irq_stack_ptr, orig_sp, sp_in;
+       unsigned long irq_stack_ptr, orig_sp;
        struct arm64_pt_regs *ptregs;
        struct machine_specific *ms;
 
-       sp_in = frame->sp;
-
        stack_mask = (unsigned long)(ARM64_STACK_SIZE) - 1;
        fp = frame->fp;
 
@@ -1612,8 +1664,17 @@ arm64_unwind_frame(struct bt_info *bt, struct 
arm64_stackframe *frame)
                        if (INSTACK(orig_sp, bt) && (INSTACK(frame->fp, bt) || 
(frame->fp == 0))) {
                                ptregs = (struct arm64_pt_regs 
*)&bt->stackbuf[(ulong)(STACK_OFFSET_TYPE(orig_sp))];
                                frame->sp = orig_sp;
-                               frame->pc = ptregs->pc;
-                               bt->bptr = sp_in;
+
+                               /*
+                                * if frame->fp == 0, ptregs->pc is a pc
+                                * where an exception in user mode was taken.
+                                * So don't update frame->pc since we have
+                                * a pseudo stack frame for exception entry.
+                                */
+                               if (frame->fp)
+                                       frame->pc = ptregs->pc;
+
+                               bt->bptr = fp;
                                if (CRASHDEBUG(1))
                                        error(INFO, 
                                            "arm64_unwind_frame: switch stacks: 
fp: %lx sp: %lx  pc: %lx\n",
@@ -1634,10 +1695,11 @@ arm64_unwind_frame(struct bt_info *bt, struct 
arm64_stackframe *frame)
 static void 
 arm64_back_trace_cmd(struct bt_info *bt)
 {
-       struct arm64_stackframe stackframe;
+       struct arm64_stackframe stackframe, cur_frame;
        int level;
        ulong exception_frame;
        FILE *ofp;
+       int end_stack = 0;
 
        ofp = BT_REFERENCE_CHECK(bt) ? pc->nullfp : fp;
 
@@ -1657,7 +1719,7 @@ arm64_back_trace_cmd(struct bt_info *bt)
                stackframe.fp = GET_STACK_ULONG(bt->bptr - 8);
                stackframe.pc = GET_STACK_ULONG(bt->bptr);
                stackframe.sp = bt->bptr + 8;
-               bt->frameptr = stackframe.sp;
+               bt->frameptr = stackframe.fp;
        } else if (bt->hp && bt->hp->esp) {
                if (arm64_on_irq_stack(bt->tc->processor, bt->hp->esp)) {
                        arm64_set_irq_stack(bt);
@@ -1703,23 +1765,9 @@ arm64_back_trace_cmd(struct bt_info *bt)
        while (1) {
                bt->instptr = stackframe.pc;
 
-               switch (arm64_print_stackframe_entry(bt, level, &stackframe, 
ofp))
-               {
-               case BACKTRACE_COMPLETE_KERNEL:
-                       return;
-               case BACKTRACE_COMPLETE_USER:
-                       goto complete_user;
-               case BACKTRACE_CONTINUE:
-                       break;
-               }
-
-               if (exception_frame) {
-                       arm64_print_exception_frame(bt, exception_frame, 
KERNEL_MODE, ofp);
-                       exception_frame = 0;
-               }
-
+               cur_frame = stackframe;
                if (!arm64_unwind_frame(bt, &stackframe))
-                       break;
+                       end_stack = 1;
 
                if (arm64_in_exception_text(bt->instptr) && 
INSTACK(stackframe.fp, bt)) {
                        if (!(bt->flags & BT_IRQSTACK) ||
@@ -1731,9 +1779,30 @@ arm64_back_trace_cmd(struct bt_info *bt)
                    !arm64_on_irq_stack(bt->tc->processor, stackframe.sp)) {
                        bt->flags &= ~BT_IRQSTACK;
                        if (arm64_switch_stack(bt, &stackframe, ofp) == 
USER_MODE)
-                               break;
+                               end_stack = 1;
+                       else
+                               arm64_print_exception_frame(bt, stackframe.sp,
+                                                       KERNEL_MODE, ofp);
+
+                       /* Next, we will display a process stack. */
+                       bt->frameptr = stackframe.sp;
                }
 
+               switch (arm64_print_stackframe_entry(bt, level, &cur_frame, 
&stackframe, ofp))
+               {
+               case BACKTRACE_COMPLETE_KERNEL:
+                       return;
+               case BACKTRACE_CONTINUE:
+                       break;
+               }
+
+               if (end_stack)
+                       break;
+
+               if (arm64_in_exp_entry(cur_frame.pc) && exception_frame) {
+                       arm64_print_exception_frame(bt, exception_frame, 
KERNEL_MODE, ofp);
+                       exception_frame = 0;
+               }
 
                level++;
        }
@@ -1912,7 +1981,6 @@ arm64_switch_stack(struct bt_info *bt, struct 
arm64_stackframe *frame, FILE *ofp
        if (frame->fp == 0)
                return USER_MODE;
 
-       arm64_print_exception_frame(bt, frame->sp, KERNEL_MODE, ofp);
        return KERNEL_MODE;
 }
 
@@ -2004,8 +2072,10 @@ arm64_print_exception_frame(struct bt_info *bt, ulong 
pt_regs, int mode, FILE *o
        ulong LR, SP, offset;
        char buf[BUFSIZE];
 
-       if (bt->flags & BT_FULL)
-               arm64_display_full_frame(bt, pt_regs);
+       if (mode == KERNEL_MODE)
+               fprintf(ofp, "--- <Exception in kernel> ---\n");
+       else
+               fprintf(ofp, "--- <Exception in user> ---\n");
 
        if (CRASHDEBUG(1)) 
                fprintf(ofp, "pt_regs: %lx\n", pt_regs);
diff --git a/defs.h b/defs.h
index d6f719c..90d8406 100644
--- a/defs.h
+++ b/defs.h
@@ -3060,6 +3060,11 @@ struct machine_specific {
        ulong *irq_stacks;
        ulong __irqentry_text_start;
        ulong __irqentry_text_end;
+       /* for exception vector code */
+       ulong exp_entry1_start;
+       ulong exp_entry1_end;
+       ulong exp_entry2_start;
+       ulong exp_entry2_end;
        /* only needed for v4.6 or later kernel */
        ulong kimage_voffset;
        ulong kimage_text;
-- 
2.8.1

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